solar water heater has two models:one is the temperature of the water way to the top of the first high to low, easy to grasp, easy to adapt to the user, but requires water to maintain water supply capacity. Guaranteed in the case of tap water is recommended to use the top of the water way. Domestic solar water heater designed to the top of the water mode, the internal structure of the tank must be reasonably designed to ensure uniformity of water, avoid the formation of water, "short"or dead. Designed using the pipe can be converted into the best type of connection drowning in the water deficiency or water stress during emergency use.